As one of electrophotographic toners for development of electrostatic latent images formed on the surface of electrophotographic photoreceptor, electrostatic recording material, etc. there has been heretofore known a microcapsule toner formed of a core and a shell. Various types of such a microcapsule toner have been proposed. For example, JP-A-59-185353 and 59-187357 (the term "JP-A" as used herein means an "unexamined published Japanese patent application") dislcose a capsule toner comprising a specific quaternary ammonium salt polymer present on the shell thereof.
However, since the polymer as described in the above cited patent applications contains halogen atoms as anions in the quaternary ammonium salt structure, it has a disadvantage that it shows a poor environmental stability, particularly humidity stability, of charging. Further, since the polymer is incorporated in the shell as one of the constituents of the shell of the capsule, it is difficult to allow only one constituent to satisfy both the desired mechanical strength and chargeability of the toner, so that selection of materials is limited.